WO2015151860A1

WO2015151860A1 - Position sensor

Info

Publication number: WO2015151860A1
Application number: PCT/JP2015/058470
Authority: WO
Inventors: 良真吉岡; 裕介清水
Original assignee: 日東電工株式会社
Priority date: 2014-04-03
Filing date: 2015-03-20
Publication date: 2015-10-08
Also published as: JP2015197878A; TW201543309A

Abstract

This invention provides a position sensor whereby even if forceful contact exhibiting a load of 13 N is applied to an optical waveguide, cores in said optical waveguide and an under-cladding layer do not undergo plastic deformation but rather quickly return to the original shapes thereof. Said position sensor comprises the following: a quadrangular sheet-shaped optical waveguide (W) in which a lattice of cores (2) is supported by a quadrangular sheet-shaped under-cladding layer (1) and covered by an over-cladding layer (3); a light-emitting element (4) connected to one end face of each linear core (2) constituting the lattice of cores (2); and a light-receiving element (5) connected to the other end face of each linear core (2). The cores (2) are set so as to have an elastic region over the tensile-elongation range from 3% to 10%, and the under-cladding layer (1) is set so as to have an elastic region over the tensile-elongation range from 5% to 140%.

Description

Position sensor

The present invention relates to a position sensor that optically detects a pressed position.

Conventionally, a position sensor that optically detects a pressed position has been proposed (see, for example, Patent Document 1). In this structure, a plurality of linear cores serving as optical paths are arranged in the vertical and horizontal directions, and a sheet-like optical waveguide is formed by covering the peripheral edge portions of the cores with a clad. The light that has propagated through each core is detected by the light receiving element at the other end surface of each core. When a part of the surface of the optical waveguide corresponding to the vertical and horizontal arrangement parts of the core is pressed with a pen tip or the like, the pressed part is recessed in the pressing direction and the core is crushed (the cross-sectional area of the core in the pressing direction is reduced). ) Since the detection level of light at the light receiving element is lowered at the core of the pressing portion, the vertical and horizontal positions (coordinates) of the pressing portion can be detected.

JP-A-8-234895

However, even if the pressing position can be detected by the deformation of the core, after the pressing is released, the core quickly returns to the original shape, and the light propagation in the core does not return to the original state. Can't prepare for pressing. The conventional position sensor has a problem that the core or the under clad layer is plastically deformed by a strong pressure (for example, a load of 13 N) and does not return to its original shape even when the pressure is released.

The present invention has been made in view of such circumstances, and even when a strong pressure of 13N is applied to the optical waveguide, the core and the under cladding layer of the optical waveguide are not plastically deformed, and when the pressure is released, The purpose of the present invention is to provide a position sensor that quickly recovers to its original shape.

In order to achieve the above object, a position sensor of the present invention includes a plurality of linear cores formed in a lattice shape, an under cladding layer that supports the cores, and an over cladding layer that covers the cores. A position comprising: a sheet-like optical waveguide; a light emitting element connected to one end face of the core of the optical waveguide; and a light receiving element connected to the other end face of the core and emitted from the light emitting element and reaching the core through the core In the sensor, the core is set in an elastic range of 3 to 10% tensile elongation, and the under cladding layer supporting the core is set in an elastic range of 5 to 140% tensile elongation. The surface portion of the optical waveguide corresponding to the lattice-shaped core portion is formed in the input region, and the pressed portion in the input region is used to attenuate the received light intensity in the light receiving element due to the pressing. Ri adopt a configuration that is specified.

In a position sensor having a sheet-like optical waveguide in which a lattice-shaped core is supported by an under-cladding layer, the inventors of the present invention are able to release the optical waveguide core and the under-cladding layer when the pressure on the optical waveguide is released. In order to quickly recover to the original shape, we focused on the tensile elongation of the core and underclad layer and repeated research. As a result, when the core is set in an elastic region in the range of 3 to 10% tensile elongation and the undercladding layer is set in the elastic region in the range of 5 to 140% tensile elongation, Even when a strong pressure of 13N is applied to the waveguide, the core and the under cladding layer of the optical waveguide are not plastically deformed, and when the pressure is released, it is quickly recovered to the original shape, and the present invention Reached.

That is, in the optical waveguide, since the core is formed in a state supported by the under cladding layer, if the under cladding layer is deformed, the core is also deformed, so that the core returns to its original shape. Even so, not only the core but also the undercladding layer needs to return to its original shape. Therefore, in the present invention, the core and the undercladding layer are defined as described above, and the core and the undercladding layer are quickly restored. The over clad layer is also formed on the under clad layer so as to cover the core. However, if the core and the under clad layer return to the original shape, the light propagation in the core is also restored to the original state. Therefore, even if the over clad layer remains deformed, it can be prepared for the next pressing.

The position sensor of the present invention has a sheet-like optical waveguide in which a lattice-like core is supported by an under-cladding layer, and the core is set in an elastic range of a tensile elongation of 3 to 10%. The undercladding layer is set to have an elastic range of 5 to 140% tensile elongation. Therefore, even when a strong pressure of 13 N is applied to the optical waveguide, the core and the under cladding layer of the optical waveguide are not plastically deformed, and can be quickly restored to the original shape when the pressure is released. That is, the position sensor of the present invention can quickly prepare for the next pressing, and is excellent in continuous detection of the pressing position.

In particular, when the core and the undercladding layer are made of epoxy resin, it is easy to set the core and the undercladding layer in the elastic range within the range of the tensile elongation.

Further, when the over clad layer is set in an elastic range of tensile elongation of 5 to 140%, the over clad layer is not plastically deformed even when a strong pressure of 13 N is applied to the optical waveguide. When the pressure is released, the original shape can be quickly recovered. For this reason, when the pressure is released, the trace of the pressure can be quickly eliminated from the surface of the optical waveguide (the surface of the over clad layer).

BRIEF DESCRIPTION OF THE DRAWINGS The 1st Embodiment of the position sensor of this invention is shown typically, (a) is the top view, (b) is the expanded sectional view. It is sectional drawing which shows the use condition of the said position sensor typically, (a) is a press state, (b) is the state which canceled the press. (A)-(d) is explanatory drawing which shows the manufacturing method of an optical waveguide typically. It is an expanded sectional view showing typically a 2nd embodiment of a position sensor of the present invention. (A) to (f) are enlarged plan views schematically showing a crossing form of lattice-like cores in the position sensor. (A), (b) is an enlarged plan view which shows typically the course of the light in the cross | intersection part of the said grid | lattice-like core.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 (a) is a plan view showing a first embodiment of the position sensor of the present invention, and FIG. 1 (b) is an enlarged cross-sectional view of the central portion thereof. The position sensor of this embodiment includes a rectangular sheet-shaped optical waveguide W in which a lattice-shaped core 2 is supported by a rectangular sheet-shaped underclad layer 1 and covered with an overcladding layer 3, and the lattice-shaped core 2. The light emitting element 4 connected to the one end surface of the linear core 2 to comprise, and the light receiving element 5 connected to the other end surface of the said linear core 2 are provided. The core 2 is in the elastic region in the range of 3 to 10% tensile elongation, and the under cladding layer 1 is in the elastic region in the range of 5 to 140% tensile elongation. In this embodiment, the over clad layer 3 is also in the elastic region in the range of 5 to 140% tensile elongation, like the under clad layer 1.

Further, the light emitted from the light emitting element 4 passes through the core 2 and is received by the light receiving element 5. And the surface part of the over clad layer 3 corresponding to the part of the lattice-like core 2 is an input region. In FIG. 1A, the core 2 is indicated by a chain line, and the thickness of the chain line indicates the thickness of the core 2. In FIG. 1A, the number of cores 2 is omitted. And the arrow of Fig.1 (a) has shown the direction where light travels.

As described above, in the position sensor having the sheet-like optical waveguide W in which the lattice-like core 2 is sandwiched between the under-cladding layer 1 and the over-cladding layer 3, the core 2 has a tensile elongation of 3 to 10%. It is a major feature of the present invention that the undercladding layer 1 is in the elastic region and in the elastic region in the range of 5 to 140% tensile elongation. By having such an optical waveguide W, the core 2 and the under-cladding layer 1 are deformed while maintaining elasticity even when a strong pressing load of 13N is applied to the input region, and the pressing is released. Then, the original shape can be quickly restored by its own restoring force. From the viewpoint of shape recovery, the core 2 is preferably in the elastic region in the range of 5 to 10% tensile elongation, and the undercladding layer 1 is in the elastic region in the range of 15 to 100% tensile elongation. That is. In this embodiment, the over clad layer 3 is also in the elastic region in the range of 5 to 140% tensile elongation, like the under clad layer 1, and therefore when the pressure is released, the surface of the optical waveguide W is released. From the (surface of the over clad layer 3), it is possible to quickly eliminate a pressing mark.

That is, for example, as shown in the sectional view of FIG. 2A, the position sensor detects the pressed position so that the back surface of the under clad layer 1 is in contact with the surface of a hard object such as a desk 30. When the portion of the input region of the over clad layer 3 is pressed with the pen tip 10a or the like in the state of being placed in place, the pressing position is detected. At this time, as described above, due to the specific elastic regions of the core 2, the under cladding layer 1 and the over cladding layer 3, the core 2 and the under cladding layer 1 are recessed while maintaining elasticity. Then, as shown in the cross-sectional view of FIG. 2B, when the pressing is released, the optical waveguide W is caused by the specific elastic regions of the core 2, the under cladding layer 1 and the over cladding layer 3 as described above. Since the position sensor quickly recovers to the original flat shape, the position sensor can be quickly prepared for the next pressing, and is excellent in continuous detection of the pressing position. The pressing position may be detected on the surface of the input area via a resin film, paper, or the like.

Examples of the material for forming the core 2, the under cladding layer 1 and the over cladding layer 3 having the above characteristics include, for example, an epoxy resin from the viewpoint of ease of setting the elastic region. From the viewpoint of ease of manufacturing the optical waveguide W, the epoxy resin or the like is preferably a photosensitive resin. The refractive index of the core 2 is set larger than the refractive indexes of the under cladding layer 1 and the over cladding layer 3. The refractive index can be adjusted by, for example, selecting the type of each forming material and adjusting the composition ratio.

In the optical waveguide W of this embodiment, a lattice-like core 2 is embedded in the surface portion of the sheet-like underclad layer 1, and the surface of the underclad layer 1 and the top surface of the core 2 face each other. The sheet-like over clad layer 3 is formed in a state where the surface of the under clad layer 1 and the top surface of the core 2 are covered. Since the optical waveguide W having such a structure can make the over clad layer 3 have a uniform thickness, it is easy to detect the pressing position in the input region. The thickness of each layer is set, for example, in the range of 10 to 500 μm for the under cladding layer 1, in the range of 5 to 100 μm for the core 2, and in the range of 1 to 200 μm for the over cladding layer 3.

Further, the elastic modulus of the core 2 is preferably set to be equal to or higher than the elastic modulus of the under cladding layer 1 and the over cladding layer 3. The reason is that if the elastic modulus is set in the opposite direction, the periphery of the core 2 becomes hard, so that the optical waveguide W having a considerably larger area than the area of the pen tip or the like that presses the input region portion of the over clad layer 3. This is because the above-mentioned portion is recessed and it is difficult to accurately detect the pressed position. Therefore, as each elastic modulus, for example, the elastic modulus of the core 2 is set within a range of 1 to 10 GPa, and the elastic modulus of the over cladding layer 3 is set within a range of 0.1 to 10 GPa. The elastic modulus of the layer 1 is preferably set within a range of 0.1 to 1 GPa. In this case, since the elastic modulus of the core 2 is large, the core 2 is not crushed by a small pressing force (the cross-sectional area of the core 2 does not become small), but the core 2 is depressed so as to sink into the under cladding layer 1 by the pressing. [Refer to FIG. 2 (a)], light leakage (scattering) occurs from the bent portion of the core 2 corresponding to the recessed portion, and in the core 2, the light receiving element 5 [refer to FIG. 1 (a)]. Since the detection level of the light decreases, the pressed position can be detected.

Next, an example of a method for manufacturing the optical waveguide W will be described. First, as shown in FIG. 3A, the over clad layer 3 is formed into a sheet having a uniform thickness. Next, as shown in FIG. 3B, the core 2 is formed in a predetermined pattern on the upper surface of the over clad layer 3 in a protruding state. Next, as shown in FIG. 3C, the under cladding layer 1 is formed on the upper surface of the over cladding layer 3 so as to cover the core 2. Then, as shown in FIG. 3D, the obtained structure is turned upside down so that the under cladding layer 1 is on the lower side and the over cladding layer 3 is on the upper side. In this way, the optical waveguide W is obtained. The under cladding layer 1, the core 2 and the over cladding layer 3 are produced by a manufacturing method corresponding to each forming material.

FIG. 4 is an enlarged view of the cross section of the central portion of the second embodiment of the position sensor of the present invention. In this embodiment, the structure of the optical waveguide W is upside down with respect to the first embodiment shown in FIG. That is, the surface of the under-cladding layer 1 having a uniform thickness is formed in a predetermined pattern with the core 2 protruding, and the over-cladding layer is formed on the surface of the under-cladding layer 1 with the core 2 covered. 3 is formed. The other parts are the same as those of the first embodiment shown in FIG. 1B, and the same reference numerals are given to the same parts. The position sensor of this embodiment also has the same operations and effects as those of the first embodiment shown in FIG.

In each of the above embodiments, each intersection of the lattice-like core 2 is normally formed in a state where all four intersecting directions are continuous, as shown in an enlarged plan view in FIG. There are others. For example, as shown in FIG. 5B, only one intersecting direction may be divided by the gap G and discontinuous. The gap G is formed of a material for forming the under cladding layer 1 or the over cladding layer 3. The width d of the gap G exceeds 0 (it is sufficient if the gap G is formed) and is usually set to 20 μm or less. Similarly, as shown in FIGS. 5C and 5D, two intersecting directions (two directions facing each other in FIG. 5C and two adjacent directions in FIG. 5D) are discontinuous. As shown in FIG. 5 (e), the three intersecting directions may be discontinuous, or as shown in FIG. 5 (f), all the four intersecting directions may be discontinuous. It may be discontinuous. Further, a lattice shape having two or more types of intersections among the intersections shown in FIGS. That is, in the present invention, the “lattice shape” formed by the plurality of linear cores 2 means that a part or all of the intersections are formed as described above.

In particular, as shown in FIGS. 5B to 5F, if at least one intersecting direction is discontinuous, the light crossing loss can be reduced. That is, as shown in FIG. 6 (a), in an intersection where all four intersecting directions are continuous, when light is focused on one intersecting direction (upward in FIG. 6 (a)), light incident on the intersection Part of the light reaches the wall surface 2a of the core 2 orthogonal to the core 2 through which the light has traveled, and is transmitted through the core 2 because the reflection angle at the wall surface is large [two points in FIG. (See chain line arrow). Such light transmission also occurs in the direction opposite to the above (downward in FIG. 6A). On the other hand, as shown in FIG. 6 (b), when one intersecting direction (upward in FIG. 6 (b)) is discontinuous by the gap G, the interface between the gap G and the core 2 is Part of the light that is formed and passes through the core 2 in FIG. 6A is reflected at the interface without passing through the core 2 because the reflection angle at the interface is small, and continues to travel through the core 2 [FIG. 6 (b), see the two-dot chain line arrow]. From this, as described above, if at least one intersecting direction is discontinuous, the light crossing loss can be reduced.

Further, in each of the above embodiments, the over clad layer 3 is also in the elastic region in the range of tensile elongation of 5 to 140%, similar to the under clad layer 1, but the over clad layer 3 has other elastic characteristics. May be used.

Further, in each of the above embodiments, an elastic layer such as a rubber layer may be provided on the lower surface of the under cladding layer 1. In this case, after releasing the pressure, the under-cladding layer 1, the core 2 and the over-cladding layer 3 recover not only to their own restoring force but also to the original shape by utilizing the elastic force of the elastic layer. be able to. Further, the under clad layer 1 may be made of the same material as that of the elastic layer, and a laminate including the under clad layer 1 and the elastic layer may be handled as one layer.

Next, examples will be described together with comparative examples. However, the present invention is not limited to the examples.

[Material for forming core, under clad layer and over clad layer]
As shown in Table 1 below, four types of epoxy resins were prepared for forming the core, and three types of epoxy resins were prepared for forming the clad (under clad layer and over clad layer). At least one of these epoxy resins was used to prepare core and clad forming materials used in Examples 1 to 5 and Comparative Examples 1 to 3, respectively. For the preparation, a photoacid generator, ethyl lactate (solvent), or the like was appropriately used.

[Tensile elongation of core and cladding]
Using each of the above forming materials, core and clad plate specimens [0.5 mm × 20 mm × 0.05 mm (thickness)] were prepared. And the tensile elongation of each test piece was measured using the tension compression testing machine (TECHNO GRAPH TG-1kN). The results are shown in Table 1 below.

[Production of optical waveguide]
First, an over clad layer was formed on the surface of a glass substrate by spin coating using the above clad forming material. The over cladding layer had a thickness of 25 μm.

Next, a lattice-like core was formed on the surface of the over clad layer by photolithography using the core forming material. The core had a width of 30 μm and a thickness of 50 μm. Note that the core could not be patterned with a material having a tensile elongation exceeding 10%.

Next, an under clad layer was formed on the upper surface of the over clad layer by spin coating using the clad forming material so as to cover the core. The thickness of this under cladding layer was 500 μm.

Then, the over clad layer was peeled off from the glass substrate. Next, the under cladding layer was bonded to the surface of the aluminum plate via an adhesive. Thus, the optical waveguide was produced on the surface of the aluminum plate via the adhesive.

[Production of position sensor]
A light emitting element (Optowell, XH85-S0603-2s) is connected to one end face of the core of the optical waveguide, and a light receiving element (Hamamatsu Photonics, s10226) is connected to the other end face of the core. To 5 and Comparative Examples 1 to 3 were produced.

[Evaluation of position sensor: continuous detection (shape recovery)]
Paper (thickness 80 μm) was placed on the surface of the input region of each position sensor via a PET film (thickness 50 μm). And the light reception spectrum was observed with the said light receiving element in the state which did not apply a load to the surface of the paper. Next, a load of 9.8 N was applied to the surface of the paper with a ballpoint pen tip having a diameter of 0.5 mm, and a light reception spectrum was observed with the light receiving element. Next, the load from the ballpoint pen tip was released, and the time from immediately after that until the light reception spectrum recovered to the light reception spectrum in the no-load state was measured. And those whose recovery time is less than 7.1 ms (CMOS scan speed) are evaluated as being excellent in continuous detection (shape recovery) of the position sensor, and those whose recovery time is 7.1 ms or more. The results were evaluated as inferior to continuous detection (shape recoverability) of the position sensor, and x was shown in Table 1 below. In Comparative Examples 1 to 3, plastic deformation was caused by applying the above load, and the shape did not recover even when the load was released.

[Evaluation of position sensor: elasticity maintenance]
Paper (thickness 80 μm) was placed on the surface of the input region of each position sensor via a PET film (thickness 50 μm). Then, after applying a load of 9.8 N with a ballpoint pen with a tip diameter of 0.5 mm to one place on the surface of the paper 30 times (1 second load at a time), It observed using the optical microscope (the KEYENCE company make, WH-Z75). Table 1 below shows that the surface having no load trace is evaluated as being excellent in elasticity sustainability, and the surface having a load trace is evaluated as being inferior in elasticity retention. It was.

From the results of Table 1 above, it can be seen that the position sensors of Examples 1 to 5 are superior in continuous detection (shape recovery) and elasticity maintenance as compared with the position sensors of Comparative Examples 1 to 3. And it turns out that the difference of the result is dependent on the tensile elongation in the elastic region of a core and a clad.

Also, in Examples 1 to 5, continuous detection (shape recoverability) showing the same tendency as in Examples 1 to 5 was obtained even if the elastic characteristics of the overclad layer were changed. This shows that the evaluation result depends on the tensile elongation in the elastic region of the core and the under cladding layer.

Furthermore, in Examples 1 to 5 above, continuous detection (shape recovery) and elasticity maintenance were evaluated with paper placed on the surface of the input region of the position sensor via a PET film. Evaluation results showing the same tendency as in Examples 1 to 5 were obtained even when the PET film and paper were not placed.

In the first to fifth embodiments, the optical waveguide is shown in a sectional view in FIG. 1B. However, the optical waveguide is shown in the sectional view in FIG. 4 as in the first to fifth embodiments. An evaluation result showing the tendency was obtained.

In the above embodiments, specific forms in the present invention have been described. However, the above embodiments are merely examples and are not construed as limiting. Various modifications apparent to those skilled in the art are contemplated to be within the scope of this invention.

The position sensor of the present invention can be used to quickly eliminate a pressing mark when detecting a pressing position and to improve continuous detection.

W Optical waveguide 1 Under clad layer 2 Core 3 Over clad layer 4 Light emitting element 5 Light receiving element

Claims

A sheet-like optical waveguide having a plurality of linear cores formed in a lattice shape, an under cladding layer that supports the cores, and an over cladding layer that covers the cores;
A light emitting element connected to one end face of the core of the optical waveguide;
A position sensor comprising a light receiving element connected to the other end face of the core and emitted from the light emitting element and reaching through the core;
The core is set in an elastic range of 3 to 10% tensile elongation, and the undercladding layer supporting the core is set in an elastic range of 5 to 140% tensile elongation.
A position characterized in that a surface portion of an optical waveguide corresponding to the lattice-shaped core portion is formed in an input region, and a pressing position in the input region is specified by attenuation of received light intensity in the light receiving element due to the pressing Sensor.
The position sensor according to claim 1, wherein the core and the under cladding layer are made of epoxy resin.
The position sensor according to claim 1 or 2, wherein the over clad layer is set in an elastic range of 5 to 140% in tensile elongation.